The present invention relates to audio systems for personal use, such as in mobile terminals and, more particularly, to speaker assemblies.
Manufacturers and designers of personal electronic devices, such as cellular radio telephones, frequently seek to reduce the overall dimensions of such devices while maintaining attractive style characteristics for the devices. One consequence of the reduced size for such devices that include a speaker is that less space may be available for the speaker. Furthermore, a variety of audio signal generation capabilities may be desired in such personal electronic devices including buzzers, voice signal generation and/or music or other higher frequency band signal reproduction and playback. Some devices include a second speaker to provide this added functionality.
As the space available for the hardware supporting the audio signal generation capabilities decreases in the personal electronic devices, it may become more difficult to support multiple sound emitting output devices and the space available for each such device may become smaller. Furthermore, increased functionality in such personal electronic devices may require more of the reduced available space to be utilized for other functionality of the device. The reduction in the size of the audio output devices may also increase the difficulty of providing a desirable loudness level for signals, such as buzzer alert signals.
One approach to providing a range of volumes in a handheld device is to use a clamshell device, such as a flip phone, including a switch indicating when the flip phone is in the open position. Responsive to the switch detecting opening of the flip phone, the acoustic level of the speaker may be lowered assuming the user is about to place the device near the user's ear. However, clamshell devices not equipped with such switches and non-clamshell type designs typically do not have the ability to anticipate that the phone is about to be moved to the user's ear. Instead, the speaker volume may be a compromise level that may result in high peak acoustic levels to a user at the earpiece or lower than desirable alerting levels as discussed above.
Some other handset device designs may include two separate speakers that are positioned in separate areas of the device. Typically, the earpiece acoustic first speaker is positioned adjacent the front face of the device by the earpiece and the second speaker, that may provide added audio functionality, is positioned under the keypad or battery or in the antenna volume as a rear-firing speaker with its own, separate, acoustic channels. However, the size of a device including two remotely located speakers may be increased to accommodate both speakers and their related acoustic channels. Such devices may also experience acoustic coupling of the speakers that may, in turn, cause increased acoustic echo.